If the two sides at Geneva are negotiating with anything like the fervor displayed by the new generation of self-appointed congressional diplomats who are bargaining like mad at the White House, arms control may be at hand.

Capitol Hill is positively awash with nuclear statesmen who shuttle between their offices and the West Wing of the White House and regale their colleagues with fresh assurances about the president's new-found "commitment" to--well, if not exactly nuclear disarmament, at least their particular version of it.

Disarmament is a many-splendored thing these days.

For instance, 91 House Democrats, who say they want nothing more than to reduce the nuclear threat, voted last month for the MX missile--that is, 100 new missiles with 10 warheads each.

They were not voting for the MX, they will tell you. They were advancing the cause of the economy-size Midgetman, the remedy and replacement for the MX. Under this peace initiative, 1,000 single-warhead missiles would be spread across the land in the interest of a more stable world.

The MX, we know now from Kenneth L. Adelman, Reagan's director of the Arms Control and Disarmament Agency, is not a "bargaining chip" at the real disarmament talks.

But, we are led to believe, it gives the Democrats who voted for it "leverage" with the president. The House negotiators, who are led by Les Aspin (D-Wis.), Albert Gore Jr. (D-Tenn.) and Norman D. Dicks (D-Wash.), say they are holding the president's feet to the fire. So far, having staked their futures on it, they have seen "flexibility" from the commander-in-chief, although admittedly not much.

The Senate striped-pants set is concentrating on another "disarmament" proposal, the so-called guaranteed mutual build-down, a program of euthanasia for elderly nukes. For every two warheads past their prime that will be retired, only one new one can be produced. Sen. Mark O. Hatfield (R-Ore.) sees this as an "escape route" from a nuclear freeze, which inconveniently halts the production of all weapons on both sides.

That one man's build-down can be another man's buildup was amply proved by Defense Secretary Caspar W. Weinberger's response to this latest effort to reduce nuclear tensions. When asked about it at an MX hearing, he responded cheerfully, "That's what we are trying to do."

Since Weinberger is one of the few people in Washington who are not suspected of pushing any kind of disarmament scheme, his acquiescence might have proved awkward for build-down fans. All the same, 43 co-sponsors in the Senate were effortlessly rounded up for this attempt to melt down the freeze movement, which enjoys much popular support.

Being simultaneously in favor of stopping the arms race and building deadlier weapons is considered perfectly logical in the Washington peace movement. Fifty House members who helped pass the nuclear freeze resolution also voted for the MX.

Sen. Joseph R. Biden Jr. (D-Del.) is one who favors both the build-down and the freeze. At the opening hearing on the proposal he sought from the Founding Fathers some little hint that there was nothing inconsistent about his "two-track" approach.

Sen. Sam Nunn (D-Ga.), one of the authors of the plan and one who likes to deal in figures and abstruse terms such as "the rapid-reloading problem," was not much help. He is against the freeze, and when pressed to explain the difference between the two approaches, he said the obvious: the build-down permits weapons modernization and the freeze does not.

Sen. William S. Cohen (R-Maine), the other author, was more compassionate and said soothingly that "many senators are for both."

Biden had no quarrel with the build-down--in fact, he was lavish in praising the brilliance of the concept, which he said had "moved the administration off dead-center," adding that he could think of "nothing else that would have moved them."

But he conducted a running debate with himself about the central question that gnaws at liberals: Does Reagan really want to disarm the world or just Congress?

There is "incredible skepticism," Biden said, and Adelman's astonishing replies about the MX at a closed session, which he later put in a letter, had escalated it. The MX, Adelman said, would be deployed unless the Soviets gave up their heavy and medium missiles.

Biden finally blurted out what he obviously thinks is Reagan's permanent position, despite the "conversion" copiously reported by his negotiating colleagues.

"We will give up something if they give up everything," he said unhappily.

That strikes some people as an apt summary of Reagan's true view of how to reach accord with the "evil empire."

What's new is the revelation that so many people on Capitol Hill share it, to one degree or another. The difference is that so few of them admit it.